The present invention relates generally to end-to-end joining of nanotubes, and, particularly to methods of end-to-end joining of nanotubes based upon physiochemical properties of the nanotube ends.
Tubular microstructures including carbon and other nanotubes have attracted enormous attention over the past decade as a result of their potential significance in microelectronic devices and nanobiotechnology (Iijima et al., Nature vol. 363, 603 (1993); Hirsch et al., Angew. Chem. Int. Ed. vol. 41, 1853 (2002)). One of the primary reasons for using nanotubes on these applications is their hollow structures that can transport biomaterials as well as electronic signals, and also can provide a space for cell growth. For this objective, the control of nanotubes in diameter and length is essential to enhance the selectivity and detection limit of nanotubes against target materials. Along with the carbon nanotubes, diacetylene nanotubes were observed by Schoen and Yager (Mol. Cryst. Liq. Cryst. vol. 106, 371 (1984)) as having assembled in water from liposomes of the two-chain chiral lipid diacetylene, 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine (“DC8,9PC”). Tubules formed from DC8,9PC have an average diameter of 0.5 μm and lengths which range from 50 to 200 μm. The size and stability of these tubules were sensitive to preparation conditions and thermal history, resulting in a non-homogenous preparation. Other work with chiral lipids bearing two diacetylenic chains has demonstrated that it is difficult to generate uniform nanotube structures from these precursors (see, e.g., Thomas et al., Science vol. 267, 1635 (1995); Spector et al., Nano Letters vol. 1, 375 (1984); Wand et al., Langmuir vol. 15, 6135 (1999); Svenson et al., Langmuir vol. 15, 4464 (1999); Seddon et al., Angew. Chem. Int. Ed. vol. 41, 2988 (2002); and Thomas et al., J. Am. Chem. Soc. vol. 124, 1227 (2002), the disclosures of which are incorporated herein by reference).
Various attempts have been made to control nanotubes diameters and lengths by changing chemical modification and fabrication method of amphiphilic diacetylene lipids. Schoen et al. have discussed method of making lipid tubules composed of chiral diacetylenic phosphocholine by a cooling process. See, U.S. Pat. No. 4,990,291. The diacetylenic phosphocholines have distinctly different endothermic and exothermic transition temperatures. Lipid tubules can be formed by hydrating a diacetylenic phosphocholine at a temperature above its endothermic transition temperature then slowly lowering the temperature. However, the tubule-like structures discussed in these publications were quite heterogeneous.
It remains desirable to develop compositions, systems and methods to improve control of nanotube dimensions.